The olive tree flowers in late April to early May in Tuscany. Differences in climate and tree cultivar result in later budding in other regions, such as southern France, where the flowers appear in late May. Each tree sets thousands of flowers, of which only about 5% will turn into olives. The flower is too small to be pollinated by the wind alone and needs the help of insects. If there is rain or hail during the olive blossom season, few olives set and the oil crop will be low and the cost of extra virgin olive oil will rise. There are both self-fertile tree cultivars, and cultivars that require a different type for cross-fertilization.